The present invention relates to steam enhanced oil recovery and to steam-containing compositions used in such processes.
Surfactants have been used in enhanced oil recovery processes. For example, various surfactants that lower the surface tension of fluids have been used in oil recovery methods using stimulation fluids. Originally, hydrocarbon surfactants were used. However, hydrocarbon surfactants are limited in their ability to reduce surface tension. Subsequently, fluorochemical surfactants have been used as surface tension depressants for aqueous stimulation fluids.
In addition, surfactants have been used in processes for decreasing the mobility of fluids in subterranean formations. For example, one method entails introducing steam and a foaming agent into a formation to form a foam having steam as its gaseous phase. The foam selectively blocks or plugs the higher permeable channels or sections of the subterranean formation and thereby directs the steam to the more impermeable, oil-bearing portions of the formation.
Due to fluctuating oil prices and the growing scarcity of oil reserves, it is very important that oil recovery processes be conducted as economically efficient as possible. Accordingly, there is a constant need in the oil industry to improve oil recovery technology.